1. Field of the Invention
The present invention relates to a process for the polymerization of mixtures comprising olefinic monomers, the polymerization of each monomer being mediated by a transition metal-containing species.
2. Description of Related Art
Non-free radical polymerizations of ethylenically unsaturated monomers are well known. These polymerizations typically use catalysts instead of initiators to effect polymerization. Examples of such polymerizations include Ziegler-Natta (ZN) polymerizations, ring-opening metathesis polymerizations (ROMP), and group transfer polymerizations. Catalysts for these polymerizations can be quite susceptible to deactivation by adventitious oxygen and water, requiring that such deactivating materials be rigorously excluded from all reagents as well as the reaction vessel.
Specifically, ZN (co)polymerizations of monoolefins, particularly .alpha.-olefins, are well known in the art. Typically, extreme care is taken to exclude both oxygen and water from these polymerizations. Likewise, ROMP (co)polymers are known in the art. Examples of ROMP processes in both inert conditions and in the presence of water, oxygen, or both are known.
Methods of producing hot melt adhesives in sealed reaction vessels are known. U.S. Pat. No. 4,810,523 describes a method for producing hot melt adhesives in which a polymerizable liquid monomer composition is introduced into a sealed reaction vessel and polymerized by ionizing radiation. The adhesive is then removed from the reaction vessel before hot melt application. The reaction can be performed in a lined cylindrical pressure vessel or a multilayer bag.
Methods of packaging pre-made hot melt adhesives and the resulting packaged adhesives are known. German Patent No. 36 25 358 describes a hot melt adhesive block in a thermoplastic film. The film is melted and mixed with the adhesive in an extrusion process.
U.S. Pat. No. 5,257,491 describes a method of packaging a thermoplastic or thermosetting hot melt adhesive in which a portion of an adhesive composition is surrounded with a plastic packaging material. The plastic packaging material does not substantially adversely affect the adhesive characteristics of a molten mixture of the adhesive and the plastic packaging material.
PCT International Publication No. WO 93/23224 describes a method for packaging hot melt adhesive compositions in which molten hot melt adhesive (made outside the package) is poured into a mold lined with a plastic film. The plastic film is meltable with the adhesive composition and blendable into the molten adhesive composition.
A method for producing thermoplastic mold materials useful for producing molded articles is described in German Patent Disclosure 1 694 837. In the described method, the polymerization material is allowed to polymerize in a hollow profile that functions as a polymerization vessel. The hollow profile may be made of the same polymer produced in the polymerization process.